Printer, printing method and printer calibration method

Abstract

A method of calibrating an electrophotographic printer ( 30 ), the printer configured with a plurality of light settings, each light setting arranged to produce a different element type, the method comprising: determining (S 10 ) a first light level required to print a first element type by applying a proportional change to a first initial light setting; and determining (S 30 ) a second light level required to print a second element type by applying substantially the same proportional change to a second initial light setting.

1. A method of calibrating an electrophotographic printer, the printer configured with a plurality of light settings, each light setting arranged to produce a different element type, the method comprising:
 determining a first light level required to print a first element type by applying a proportional change to a first initial light setting; and 
 determining a second light level required to print a second element type by applying substantially the same proportional change to a second initial light setting. 
 
     
     
       2. The method of  claim 1  wherein the step of determining the first light level comprises:
 operating the printer at an initial light setting to produce printed output; 
 assessing the printed output; 
 adjusting the light setting by an adjustment factor to produce a desired printed output and thereby determining said first light level. 
 
     
     
       3. The method of  claim 2  wherein said assessing comprising measuring the dot area of the printed output or other property that is dependent on the dot area of the printed output. 
     
     
       4. The method of  claim 2  comprising:
 operating the printer to print the first element at a light setting under a first set of print conditions; 
 applying the adjustment factor to the light setting so as to achieve printing of the first element at a required dot area; and 
 storing said adjustment factor. 
 
     
     
       5. The method of  claim 1  comprising printing to produce a printed output having a plurality of different element types, wherein two or more of the element types are printed at a light levels calculated using said proportional change. 
     
     
       6. A method of printing comprising calibrating a printer according to  claim 1  and printing with said calibrated printer. 
     
     
       7. A laser printer comprising a laser and a processing unit for calibrating the source of the laser for printing a plurality of different print elements according to  claim 1 . 
     
     
       8. The method of  claim 1 , wherein the determining comprises determining the second light level required to print the second element type by applying to the second initial light setting the same proportional change that is applied to the first initial light setting. 
     
     
       9. The method of  claim 1 , wherein the first and second element types correspond to different respective print elements selected from: single pixels; pixels that form part of a text edge; pixels that form part of a barcode; and pixels that form part of a halftone image. 
     
     
       10. The method of  claim 1 , wherein the first and second initial light settings correspond to different laser intensity levels. 
     
     
       11. An electrophotographic printer comprising a light source for producing printed output, the printed output containing a first print element type, a sensor for measuring a print parameter of the printed output, a controller for controlling the optical output of the light source, the controller being configured to make an adjustment to the optical output of the light source in accordance with measurements made by the sensor to achieve a desired dot area for the first print element type wherein the controller is arranged to use said adjustment to correct the optical output of the light source to print other types of print element.